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Chromomere
 Bead like projections – along entire length of polytene
chromosome
 Heavier stained than inter-chromomeric regions
 Clear in dipteran salivary gland chromosome as dark bands
 Genes are located within chromomere
 One chromomere – single gene
 Evidence – local coiling of continuous DNA thread
Chromomere
Chromomere
 Vary in size
 Chromomere next to centromere – larger and progressively
smaller towards chromosome ends
 Number is constant – polytene chromosome
 Serve as reliable morphological characteristic
Telomere
 Two ends of chromosomes – end caps of chromosomes
 Highly stable and don’t fuse or unit with telomers of other
chromosomes
 If telomeres are damaged/removed – end are highly unstable
and fuse with broken ends of other chromosomes – resulting
in translocations or ring chromosomes
 Structural identity and individuality of chromosome is
maintained due to telomeres
 Telomeres – enlarged terminal chromomeres
 Sometimes show centromeric activity - neocentromere
Telomere
 Two distinct regions
 Protelomeres: terminal deep staining structure with sharp
limits, three large chromomeres
 Eutelomere: weakly staining sub-terminal region adjacent to
protelomeres
 One compound telomere –
eight chromomeres
 Irregular folded chromatin
fibres loop back into
chromatid
Telomere
 Prevent shortening of chromosomes during cell division
 Made up of both DNA and proteins
 Sequence motif ‘TTAGGG’ is highly conserved
 Retrotelomeres: composed of large number of terminal
repeats, clustered around chromosome ends